Katrina

[jamiebk]

If we get one, a year from now you'll see me living under my desk at work.

Hmmph. Neither the PiqOT household nor mine will suffer excessively from floods: we both live on nifty hills with a low spot nearby. There could be access problems, though. And while Piq has an alternate shelter under her desk at work, my desk is a no-go. My cubicle is at a mean elevation of about nine feet above sea level.

In case of floods, though, I can go look at the rooftops of several shopping centers that were built in various riverbeds.

And what of a Tsunami???

[Selma in Sandy Eggo]

And what of a Tsunami???

That's a flood of salt water, right? My desk at work will still get very wet indeed but I expect my building will survive. It was poured in place in 1938/39 and stands on actual rock, rather than fill sand. Home will be OK due to elevation, gravity, and suchlike reliable things. Piq's home and desk both should be OK. Coastal features may be rearranged...

[Serenity]

I thought tsunamis just hit asian coasts; if they come to this way, are they "way off course" or are they just named "surf's up dude"?

[jamiebk]

I thought tsunamis just hit asian coasts; if they come to this way, are they "way off course" or are they just named "surf's up dude"?

Unfortunately, the US coast and particularly the Pacific North West has an enormous risk of Tsunami. It's quite frightening to think about the consequences. We can't do anything about the event, but we can prepare for evacuation. Again, unfortunately, the PNW tsunamis from Alaska earthquakes etc. won't allow enough time before they hit to evacuate. I just hope that I am not around at the time.

[Serenity]

Have you been underwater during rough weather? Is there a depth that you can stand where you are unaware of the trouble above?

[jamiebk]

Have you been underwater during rough weather? Is there a depth that you can stand where you are unaware of the trouble above?

Actually, yes. In fact, there were scuba divers in the water when the great tsunami hit Banda Ache. They were near the floor of the ocean about 80 feet down when they were hit with a swell and swept a bit, but were largely unaware of the magnitude of the event. Ocean swells tend to dissipate the deeper you go. When we dive and its a little rough (larger swells) we head for deeper water to avoid the "sloshing".

[Serenity]

How deep can you go without worrying about getting back to the surface with insufficient oxygen? ("inquiring minds want to know")

[jamiebk]

How deep can you go without worrying about getting back to the surface with insufficient oxygen? ("inquiring minds want to know")

It's not air consumption that is usually the problem. It is usually depth and decompression time...however, that could lead to an out of air situation. Here's why:

The deeper we go, the more nitrogen from the air we breath is pushed into our bodies. Recreational diving is based upon bottom times that allow the diver to make an ascent without the need for decompression stops along the way to "off-gas" nitrogen. Here is a typical "Dive table" for calculating allowable bottom time: http://www.tdconline.com/tables/table.htm
On average, the max depth for a recreational diver is about 130 feet. This allows only about 5 minutes of bottom time. After that, you must start heading up at a rate not to exceed 30 feet per minute. At this depth, it would take over 4 minutes to surface. Most divers can get 50-80 minutes on a tank of air. So as you can see, a on simple "down and back" dive from 130 feet, you would probably not run out of air. You must always surface with at least 500 pounds per sq. inch (about 50 bar) of air (pressure) in your tank. A typical tank is aluminum and holds 80 cubic feet of air at 3000 PSI.

In considering air consumption however, you must take into consideration that as you descend, your air consumption increases dramatically. This is due to compression of the air as you experience increased compression from water pressure. Each 33 foot decent equals one "atmosphere" of pressure. Boyle's law dictates the compression rate and if you are a real "geek-a-saurus" you might find this article interesting: http://www.mindspring.com/~divegeek/estimating.htm

Essentially though, at 130 feet, you are at 5 atmosphere's and will use air at a rate 5 times greater than that at the surface.

Say your surface rate is 25 pounds per minute (probably a decent average), and we want to know how fast will we use 2000 pounds (2/3 of our tank) of air at a depth of 75 feet. Here is an equation that works for calculating air use:

SAC - Surface air consumption
DCR - Depth Consumption Rate

SAC Rate = (DCR x 33) / (Depth + 33)
DCR = SAC Rate x (Depth + 33)/33

Dropping our numbers into the handy equation we get: DCR = 25(SAC) x (75 depth + 33)/33 or DCR = 25 x 108/33 or DCR = 81.81

This means at a depth of 75 feet, we will use 81.81 pounds of air per minute. Dividing this into the 2000 pounds, we see this amount of air would last 24.4 minutes.

At 132 feet this comes out to DCR = 25 X 165/33 or DCR of 125 pounds per minute. Dividing the 125 pounds into 2000 PSI we would have about 16 minutes of air at 132 feet. That would (should) leave enough to make a controlled ascent to the surface. However, if a diver exceeds the recommended "no decompression" time guidelines then he must make stops at various higher depths to allow nitrogen to exit the tissues. If the bottom time results in deco stops of 10-15 minutes (and they could) then the diver has a problem and a decision. i.e. run out of air and die, or surface after decompressing as long as possible, surface and possibly risk decompression sickness (the bends).

The lesson here is to never, never, ever exceed your limits or your abilities.

OH...BTW, we all carry dive computers that calculate and adjust our allowed bottom time so that we can stay within the limits. We also keep a close eye on our air pressure gauge to make sure that we are not exceeding our limits. We start for the surface with 750 pounds and should be at the surface with 500. All dive durations, no matter the depth consider air usage first and foremost. Some dive computers are "air integrated" and can actually estimate "time to out of air". However, there is no substitute for conservatism, safety, knowledge and experience.

This is WAY more than you probably wanted to know. If you take a scuba certification class you will learn all of this.

[Serenity]

WOW! That's still awesome to know.....although I'm surprised there is no calculation that takes into effect the weight of the diver or the potential calories they may burn during a dive....as long as they get out alive ix all that really maters

[jamiebk]

:shock: WOW! That's still awesome to know.....although I'm surprised there is no calculation that takes into effect the weight of the diver or the potential calories they may burn during a dive....as long as they get out alive ix all that really maters

Those things can have an effect on how fast and how much nitrogen a body absorbs (as well as general health, fitness, medications, degree of exertion etc.) Once you have an approximate on your Surface Air Consumption rate however, you can do the estimates. Still, experience teaches much in this regard. And...these are all based on averages and estimates...there is no absolute. You should see the breathing rate when someone is excited (or panicked) for instance. I've seen guys burn a tank in less than 20 minutes.

Now would you like to know about how alternate breathing gasses such as 32% or 36% EAN (Nitrox) affect all of this?

[Serenity]

HIC! Shooooooor!...... Maybe you should present this at a "town meeting" with "Ross Perot pie charts"... , instead of practicing on me

[barfle]

I thought tsunamis just hit asian coasts; if they come to this way, are they "way off course" or are they just named "surf's up dude"?

There was a tsunami that hit northern California and Oregon in 1964 that killed several people. It was the result of an earthquake that almost leveled Anchorage, Alaska on Good Friday.

In Sitka, Alaska, they have a tsunami warning system.

[Haggis@wk]

I thought tsunamis just hit asian coasts; if they come to this way, are they "way off course" or are they just named "surf's up dude"?

There was a tsunami that hit northern California and Oregon in 1964 that killed several people. It was the result of an earthquake that almost leveled Anchorage, Alaska on Good Friday.

In Sitka, Alaska, they have a tsunami warning system.

I can't remember where I saw it but there was a tsunami in Alaska in the late 50s or early 60s when a huge land slide caused a massive tsunami in an uninhabited area. Some fishing boats were there and several were swamps or capsized.

Oh. I did some googling and found it was in 1958. Here's a summary of that one and the predicted danger the Canary Island pose.

[Haggis@wk]

I guess what with Kentucky being a red state the Barack Obama and FEMA can't be bothered helping the suffering Americans trying to cope with a massive ice storm that has left them powerless.

In some parts of rural Kentucky, they're getting water the old-fashioned way — with pails from a creek. There's not room for one more sleeping bag on the shelter floor. The creative are flushing their toilets with melted snow.

At least 42 people have died, including 11 in Kentucky, and conditions are worsening in many places days after an ice storm knocked out power to 1.3 million customers from the Plains to the East Coast. About a million people were still without electric Friday, and with no hope that the lights will come back on soon, small communities are frantically struggling to help their residents.

One county put it bluntly: It can't.

"We're asking people to pack a suitcase and head south and find a motel if they have the means, because we can't service everybody in our shelter," said Crittenden County Judge-Executive Fred Brown, who oversees about 9,000 people, many of whom are sleeping in the town's elementary school.

Local officials were growing angry with what they said was a lack of help from the state and the Federal Emergency Management Agency. In Grayson County, about 80 miles southwest of Louisville, Emergency Management Director Randell Smith said the 25 National Guardsmen who have responded have no chain saws to clear fallen trees.

"We've got people out in some areas we haven't even visited yet," Smith said. "We don't even know that they're alive."

Smith said FEMA has been a no-show so far.

"I'm not saying we can't handle it; we'll handle it," Smith said. "But it would have made life a lot easier" if FEMA had reached the county sooner, he said.

FEMA spokeswoman Mary Hudak said some FEMA personnel already are in Kentucky working in the state's emergency operations center and that more will be arriving in coming days. Hudak said FEMA also has shipped to 50 to 100 generators to the state to supply electricity to facilities like hospitals, nursing homes, and water treatment plants.

Can you imagine the media reaction if this were George W. Bush? Hell, we're still hearing about Hurricane Katrina nearly four years later.

This was a freebee for Obama, non-political crisis, natural disaster, send in the troops, take a helicopter flight, look concerned, etc and it looks like he’s blown it.

Fortunately, the MSM won’t ask any questions. Heck, if Katrina happens this summer most of us will read about “strong winds and partial flooding in Cuba….”

[Shapley]

The storm passed through on Tuesday. Friday, President Obama declared Missouri a disaster area.

President Bush signed a disaster declaration for Louisiana and Mississippi on August 29th, the same day the Hurricane Katrina made landfall. But he was blamed for his slow response...

[jamiebk]

FEMA's broken...it will take a while to fix it (if it can be fixed).

[Shapley]

FEMA doesn't sign the disaster declaration, the President does.

[jamiebk]

he can only sign that which is presented to him for signing....

[Haggis@wk]

he can only sign that which is presented to him for signing....

Heh. You're an intelligent guy so tell me. Did that sound as lame writing it as it did when I read it????

[analog]

FEMA's broken...it will take a while to fix it (if it can be fixed).

C Northcote Parkinson is probably right , some things are best understood by those nearest to them hence are best left decentralized. I think disaster recovery fits that category.

Existence of FEMA is a bad idea sired by another bad idea. FEMA was created to administer Johnson's National Flood Insurance Program, both are just more red bricks in the road to socialism.

Raising New Orleans above sea level might be a good Corps of Engineers project but pumping it out should be a local enterprise.

That's my opinion.

a.